MALACOZOA. CEPHALOPODA. 21 



suckers, and forming organs of locomotion and prehen- 

 sion. Brain-ganglion in a cartilaginous cavity in the 

 head ; two eyes formed of numerous membranes, and 

 covered by skin, which is transparent in front ; ears, a 

 small cavity on each side, near the brain, without ex- 

 ternal tube, and containing suspended a membranous 

 sac, in which are a limpid fluid and a small compact 

 ossiculum. Some species naked, others partially con- 

 tained in a shell. 



The Cephalopoda may be primarily divided into three 

 orders: — 1. Cryptadibranchiata, 2. Siphonifera, and 

 3. Foraminifera ; but as our species are not numerous, 

 it is inexpedient to offer any more general observations. 

 The Foraminifera probably belong to a different series ; 

 but as their nature is not yet clearly understood, and as 

 they have usually been placed among the Cephalopoda, 

 we may for the present consider them as belonging to 

 that class. Several of the species are very abundant 

 along our coasts, and some, not hitherto observed in 

 other parts of Scotland, have occurred to me. They 

 will be found among fine shell-sand, or adhering to dead 

 shells, corallines, and other objects brought up by the 

 fishing-lines. Although very minute, all the species 

 here described may be distinctly seen with the aid of a 

 good lens. 



SrXOFSIS OF THE ABERDEEXSHir.E SPECIES. 



ORDER I.— CErHALOPODA CRYPTADIBRANCHIATA. 



Branchiae laminated, concealed within the mantle ; 

 head with eight arms, to mIucIi are sometimes added 



